Fuse clamp

ABSTRACT

A fuse holder for cylindrical cartridge fuses having axially protruding terminal blades is provided with floating clamp members to grip and electrically connect with the fuse which allow for dimensional and alignment errors of the fuse or the holder.

United States Patent Inventor seph A. Genova Newlington, Conn.

App]. No. Filed Patented Assignee Dec. 5, 1969 Jan. 1 l, 1972 Arrow-Hart, Inc.

Hartford, Conn.

[54] FUSE CLAMP 6 Claims, 6 Drawing Figs.

I 5 l l [50] Field of Search l-l0lr 13/62 [56] References Cited UNITED STATES PATENTS 2,077,587 4/1937 Rowe 339/259 F 2,677,116 4/l954 Ritter 339/64 M FOREIGN PATENTS 544,454 4/1942 Great Britain 339/!50 F Primary Examiner-Joseph H. McGlynn Almrney- Davis, Hoxie, Faithful] & Hapgood ABSTRACT: A fuse holder for cylindrical cartridge fuses having axially protruding terminal blades is provided with floating clamp members to grip and electrically connect with the fuse which allow for dimensional and alignment errors of the fuse A 32 a A 5/ 5 4 l-fiki 55 PATENIEU m1 1 1372 m ol ' M van for Joseph A. 66/70 (/0 Affomeys I FUSE CLAMP ,-.The present invention is concerned with improvements in fuse holder structuresfor usewith cylindrical cartridge fuses of the type having axially protruding fiat contact blade terminals. The holder comprises a base member and a fuseretaining member. The base member is-ordinarily secured to an electrical panel and the wires of the circuit to be fuse protected are connected to terminals on the base'member. The fuse-retaining member fits within the base member and is provided with clamp means which retain the fuse by its terminal blades and is provided with contact blade members which engage with contact blade-receiving clamp members in the base portion to thereby secure the fuse-retaining member in position in the base member and to establish the electrical circuit through the fuse. The fuse-retaining member may be provided with an electrically insulated handle so that the fuse may be accessed for replacement by pulling the fuse-retaining member out of the base member. The fuse is then removed from the fuse-retaining member and the fuse link renewed or a new fuse cartridge substituted. The fuse retaining member including the new fuse is then returned to its position within the base member.

The manner in which the terminal blades of the fuse are received and gripped in the fuseretaining member, and the manner in which the fuse-retaining member is received and secured in the base portion are of particular importance to the structure of the present invention. The various elements which perform these functions are arranged to be limitedly movable with respect to each other. This floating arrangement accommodates minor alignment and dimensional variations to improve ease of assembly and to reduce contact resistance heating of the various current carrying parts.

The structure of thepresent invention will be described with reference to the drawings in which:

FIG. 1 is an elevational view in section taken in the plane 1-1 of FIG. 2,

FIG. 2 is an end view in section taken along the line 22 of FIG. 1,

FIG. 3 is a view showing a portion of the underside of the fuse-retaining member,

FIG. 4 is a perspective view of a portion of the fuse-retaining member, I

FIG. 5 is an elevational view of the and FIG. 6 is an end view in section taken along line 66 of FIG. 5.

The fuse holder of the present invention comprises a base member 50 and a fuse-retaining member 10. The fuse is a conventional cartridge-type fuse which has a cylindrical body with axially protruding contact blade portions 21 at either end. Such fuses are frequently designed so as to permit their disassembly for replacement of the fusible link which is enclosed within the cylindrical body of the fuse. The fuse 20 is retained in the fuse-retaining member 10 by means of spring acting clamp members 12 which grip the protruding terminal blade portions 21 of the fuse. The fuse retaining member 10 is provided with contact blades 14 which are received in spring acting clamp members 51 in the base portion 50. Clamp members 51 are similar in construction to clamp members 12. Electrical terminals 53 on the base member 50 permit the connection of wiring. The circuit through the fuse is established by electrical contact among the several clamp and blade members.

Each end of the fuse-retaining member 10 includes a spring acting clamp member 12 into which the terminal blade portion 21 of a fuse tightly fits. As is best seen in FIGS. 4 and 6, the fuse clamp members 12 are secured by means of a screw 18 and nut 16 to protruding contact blade member 14 to form a rigid assembly. This assembly of fuse clamp member 12 and contact blade member 1-4 is not fastened to the plastic body 13 of the fuse-retaining portion 10. The assembly is captured within the molded plastic body 13, but is free to move limitedly with respect to the body 13. A series of protrusions or lugs 31-33 are molded integral with the plastic body 13 fuse-retaining member,

and form therein a reentrant cavity "toretain the assembly of the fuse clamp 12 andcontact blade '13. Clearances between each of the protruding members 31-33 and the assembly permit the latter limited movement with respect to the body 13 but prevent withdrawal of the assembly from the body. This limited freedom of movement'of'tlieassembly'withrespect to the body accommodates dimensionalvariat'ion among fuses and between the fuse-retaining member 10 and the base member 50. The floating action of the asseniblyof the fuse clamp and contactblade prevents the transmission of stress or force to the plastic body 13. Similarly, the self-aligning ability of the various contacting members automatically establishes and preserves the best possible electrical contact. Heating of the contacting parts due to electrical contact resistance is reduced. 7

' The captured nature of the assembly of fuse clamp member 12 and contact blade 14 within the'reentrant cavities of the fuse-retaining mmber 10 necessitates that the parts 12 and 14 of the assembly be individually placed withinthe body 13 and assembled in place. The individual pieces 12 and 14 can be manipulated into position within the confines of the cavity defined by protrusions 31-33 of the body 13, but once assembled together'with screw 18 and nut 16, the assembly cannot be removed.

Base member 50 is a boxlike structure into which the fuseretaining member 10 fits in the manner of a cover or lid. Base member 50 is provided with electrical terminals 53 which may include screws or bolts to which the wiring of the circuit to be protected by the fuse is connected. Terminals 53 are mechanically and electrically connected to clamp members 51 in the base portion and fastened thereto by conventional fastener means such as screw 55. Te'rminal'members 53 with the ,associated clamp members 51 are fastened into the base member 50 by means of screws 56 or the like.

The fuse-retaining portion 10 including the fuse 20 is received within base portion 50 and retained therein by the spring action of clamps 51 which frictionally engage contact blades 14 associated with the fuseretaining member 10. The fuse-retaining member 10 may include a handle 11 insulated from the current carrying portions of the structure to provide for ease of removal of the fuse-retaining member 10 from the base member 50 when necessary.

Dimensional and alignment variations between the fuse retaining member 10 and the base member 50 are accommodated by the floating action of the contact blade members 14 which, along with fuse clamp members 12, are free to float or move with respect to the body 13 of the fuse-retaining member 10. The structure of the present invention, by virtue of the aforementioned floating action, insures the establishment of low-resistance electrical contacts between the fuse terminal blades 21 and clamps 12 as well as between base member clamps 51 and the contact blades 14 which they receive. This improved self-aligning feature improves electrical contact to reduce heating of the parts and assists in assembly and disassembly of the base with the fuse-retaining portion.

In previously known fuse holder structures the various metal contact pieces are simultaneously assembled together and affixed to the plastic moldings by attachment means such as screws or rivets. The thermosetting plastic-molding compounds employed in the manufacture of such electrical hardware tend to shrink with age thereby causing the assembly to loosen with the result of heat generation due to the increased contact resistance among the loosened pieces. The present invention avoids the consequences of age shrinkage of the plastic by rigidly assembling the metal contact pieces independently of the plastic moldings and affixing the rigid assemblies to the plastic moldings by entrapment within reentrant cavities in the moldings. Later shrinkage of the plastic has no effect upon the integrity of the assemblies.

Iclaim:

1. In a fuse holder for cylindrical cartridge fuses, said fuse holder comprising a fuse-retaining member and a base member adapted to receive the fuse-retaining member, the fuse-retaining member having a pair of fuse clamp members adapted to spring engage the terminal ends of the fuse, the improvement which comprises associating the fuse clamp members with the fuse-retaining member by capture within reentrant cavities in the fuse-retaining member with clearance such that the fuse clamp members are permitted limited freedom of movement with respect to the fuse-retaining member, the fuse clamp members each comprising a rigid assembly of a fuse-engaging spring member and a further member, the assemblies being larger than the entrance of the reentrant cavities.

2. The fuse holder of claim 1 wherein the reentrant cavities of the fuse-retaining member each include a plurality of projecting lugs which overlie portions of each of the fuse clamp members to capture them within their cavities.

3. The fuse holder of claim 1 wherein the fuse-retaining member is provided with blade contacts electrically connected to said fuse clamp members and the base member is provided with spring acting clamp members adapted to engage said blade contacts to thereby retainsaid fuse-retaining member within said base member, said base clamp members being electrically connected to wiring terminals on said base members.

4. The fuse holder of claim 3 wherein the blade contacts and the fuse clamp members are rigidly assembled together and that assembly is captured within the reentrant cavity.

5. The fuse holder of claim 4 wherein the reentrant cavities of the fuse-retaining member each include a plurality of projecting lugs which overlie portions of the rigid assemblies of blade contacts and fuse clamp members to capture the rigid assemblies within the cavities.

6. The fuse holder ofclaim 5 wherein the fuse to be held is a cylindrical cartridge fuse having axially extending terminal blades and the fuse clamp members are shaped so as to spring engage the terminal blades of the fuse.

I! i a: w w 

1. In a fuse holder for cylindrical cartridge fuses, said fuse holder comprising a fuse-retaining member and a base member adapted to receive the fuse-retaining member, the fuse-retaining member having a pair of fuse clamp members adapted to spring engage the terminal ends of the fuse, the improvement which comprises associating the fuse clamp members with the fuseretaining member by capture within reentrant cavities in the fuse-retaining member with clearance such that the fuse clamp members are permitted limited freedom of movement with respect to the fuse-retaining member, the fuse clamp members each comprising a rigid assembly of a fuse-engaging spring member and a further member, the assemblies being larger than the entrance of the reentrant cavities.
 2. The fuse holder of claim 1 wherein the reentrant cavities of the fuse-retaining member each include a plurality of projecting lugs which overlie portions of each of the fuse clamp members to capture them within their cavities.
 3. The fuse holder of claim 1 wherein the fuse-retaining member is provided with blade contacts electrically connected to said fuse clamp members and the base member is provided with spring acting clamp members adapted to engage said blade contacts to thereby retain said fuse-retaining member within said base member, said base clamp members being electrically connected to wiring terminals on said base members.
 4. The fuse holder of claim 3 wherein the blade contacts and the fuse clamp members are rigidly assembled together and that assembly is captured within the reentrant cavity.
 5. The fuse holder of claim 4 wherein the reentrant cavities of the fuse-retaining member each include a plurality of projecting lugs which overlie portions of the rigid assemblies of blade contacts and fuse clamp members to capture the rigid assemblies within the cavities.
 6. The fuse holder of claim 5 wherein the fuse to be held is a cylindrical cartridge fuse having axially extending terminal blades and the fuse clamp members are shaped so as to spring engage the terminal blades of the fuse. 